WASHINGTON: Scientists, including one of Indian-origin, have uncovered a survival mechanism that occurs in breast cells that have just turned premalignant - cells on the cusp between normalcy and cancers - which may lead to new methods of stopping tumours.

The Salk Institute researchers found that a protein known as transforming growth factor beta (TGF-beta), considered a tumour suppressor in early cancer development, can actually promote cancer once a cell drifts into a pre-cancerous state.

The surprising discovery raises the tantalising possibility that, with novel treatment, some cancers might be prevented before they even develop, researchers said.

"This study offers both significant insights into early cancer development and a new direction to explore in cancer treatment. It would be fantastic if a single agent could shut down both advanced cancer and cancer that is primed to develop," said Beverly M Emerson, study's senior author.

The researchers conducted this study to learn exactly how p53, a known tumour suppressor, and TGF-beta interact in cancer development.

The team examined premalignant as well as cancer cells from breast and lung tumours and matched normal and premalignant breast cells from healthy women provided by scientists at the University of California San Francisco.

They found that TGF-beta can interfere with cells' damage responses in premalignant or cancer cells. They found that TGF-beta halts both the transcription of the p53 gene - the process by which cellular machinery reads the DNA code for a gene - and the subsequent process by which the corresponding p53 protein is produced, known as translation.

This could explain why, in about half of the breast tumours, including premalignant lesions, when TGF-beta1 signalling was highly activated, the levels of p53 were reduced, and vice versa if the TGF-beta1 pathway was reduced, there were high levels of p53.

The new findings shed light on how premalignant and early cancer cells are able to withstand the assault of chemotherapy and other treatments.

It may explain why 77 per cent of breast cancers have a normal p53 gene, and it further suggests a way that cancer cells can use both to metastasise and survive the journey to organs where they set up a new home.

"Because it helps cells avoid death, TGF-beta can reduce the negative impact that the metastatic process has in the cancer cells," Lopez-Diaz said.

Other authors of the study published in journal Molecular Cell include Sri Kripa Balakrishnan, from Salk; Philippe Gascard, Jianxin Zhao, and Thea D Tlsty, from the University of California San Francisco; and Sonia V del Rincon and Charles Spruck, from Sanford Burnham Medical Research Institute.